GlueX Start Counter Meeting, October 15, 2020

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GlueX Start Counter Meeting
Thursday, October 15, 2020
10:00 am EDT
BlueJeans: 556 286 544


  1. Announcements
  2. Review minutes from the last meeting
  3. Calibration and Efficiency
  4. Dark Rate Studies
  5. Action Item Review


Present: Rupesh Dotel, Mark Ito (chair), Simon Taylor, Beni Zihlmann

There is a recording of this meeting on the BlueJeans site. Use your JLab credentials to gain access.

Review minutes from the last meeting

We went over the minutes from August 20 without a lot of comment.

Calibration and Efficiency

  • Calibrations for the 2019-11 run period look to be in good shape.
  • The group reminded the chair that the overall quality of the start counter data is monitored by the group that Sean Dobbs has organized to look at monitoring histograms. Rupesh is part of the team responsible for the start counter plots.

Dark Rate Studies

Beni led us through his recent log book entry showing final results from his analysis of the "dark rate" runs taken to date. See the plot below. The downward slope indicates an increase in the dark rate as a function of time.

Sctest usesamples.gif

We had a brief discussion of how to judge this data and possible degradation of the performance of the start counter in general. Rupesh has reported a slight increase in timing resolution, at the 10% level, over the years. Simon reminded us of the spec of 350 ps for timing resolution; that is a relevant benchmark.

Action Item Review

  1. Document calibration procedure (Rupesh)
  2. Reproduce Beni's dark current results. (Tolga)
  3. Revisit Yi's study of SiPM annealing. (Mark, Beni)
  4. Look up type of SiPMs used in start counter. (Mark)